The disclosed technology relates generally to recording channels, and more particularly to providing adaptive target optimization for recording channels.
With the continuing demand for high-density digital storage systems, various techniques have been applied to increase the capacity of these systems. For example, in magnetic media storage, many manufacturers are using perpendicular recording rather than traditional longitudinal recording to pack more information into a smaller area. However, as storage densities are pushed to their limits and beyond, the amount of signal distortion on information-carrying signals have increased dramatically. Thus, detectors are heavily relied upon to interpret the information in these highly distorted signals. For example, Viterbi detectors with noise-whitening filters have been developed to combat signal-dependent noise associated with reading data from a recording channel.
The performance of a detector is affected by the value of the target of the recording channel. The target of a recording channel refers to a set of registers that can be programmed to achieve different channel responses. Based on the current operating conditions and device manufacturing variations, the target that produces the best detection performance may vary from device to device and/or from time to time. Current systems select a target by evaluating the performance of the detector for all possible values of the target. Such an exhaustive search can be time consuming and impractical to perform in real-time. For example, for a target with three programmable registers—or three “taps”—where each tap can be programmed with a value from zero to 15, the system would need to evaluate over 3300 different target tap combinations in order to choose a target.